Solution : True In a shared block prevents need another user from performing DDL or DML operations on the table. The shared lock is automatically obtained when the select...for Update command is executed. There is a lock known as share row exclusive, when this is lock is used then the whole table can be seen by the other user. Similarly the other users can see all the rows in the table, but they cannot perform DDL or DML operations on the table. When this is used in the shared mode then it will automatically locks from updating of the table..